The invention relates to an interstitial ablation device and method for performing tissue ablation, and in particular, to an improved interstitial ablation device providing enhanced electrode placement and control.
Ablation devices can be used to treat tumors in the body. In particular, ablation devices can be used to treat benign prostatic hypertrophy or hyperplasia (BPH), a condition resulting in an enlargement of the prostate gland. This is a common medical problem typically experienced by men over 50 years of age. Hyperplastic enlargement of the prostate gland often leads to compression of the urethra, which results in obstruction of the urinary tract.
An ablating needle can be used with a cystoscope to treat BPH by ablating a prostatic adenoma, which is a benign tumor inside the prostate. To perform the ablation procedure, a physician inserts a distal end of the cystoscope into the urethra of a patient while viewing the advance through an eye piece of the cystoscope. The needle electrode is also introduced into the urethra through a working channel of the cystoscope. The cystoscope and the needle electrode are typically introduced inside the urethra sequentially. The distal end of the needle electrode is positioned adjacent the prostate near the prostatic adenoma. The physician then causes the needle electrode to penetrate the urethral wall, such that it is positioned inside the prostatic adenoma. Radiofrequency (RF) energy is applied to the needle electrode to coagulate tissue surrounding the electrode. Coagulation causes necrosis of the prostatic adenoma, resulting in atrophy of the prostate and a reduction in the compressive forces that interfere with urine flow through the urethra.
During the ablation procedure, it is important that the needle electrode be positioned precisely, because inaccurate electrode placement can cause incontinence in the patient. Visualization is typically provided by inserting the needle electrode through a cystoscope. One disadvantage of the ablation device insertable through a cystoscope is that it is difficult to feed the device through a working channel of the cystoscope and requires a lot of juggling which can make accurate placement of the needle electrode difficult. Moreover, it is often difficult to observe the distal tip of the needle electrode as the electrode penetrates the urethral wall, because the distal end of the electrode is typically deflected in order to penetrate the urethral wall while the viewing device itself does not deflect along with the needle electrode.
Existing interstitial ablation systems are also uncomfortable for the patients and cumbersome for the physician performing the procedure. Most cystoscopes and ablation systems integrating imaging devices tend to be rigid and uncomfortable for patients when inserted through a body lumen such as the urethra. The systems also have numerous knobs and dials that the physician must adjust for controlling needle deployment, fluid introduction, and application of RF energy.
Thus, there remains a need for an interstitial ablation device that provides accurate electrode placement and better control of the electrode, reduces patient discomfort and simplifies the process of performing ablation.
In one aspect, the invention features a deflectable interstitial ablation device. In one embodiment, the device includes an elongated housing, an electrode mounted within the elongated housing, a driver coupled to the electrode, an imaging device integrally mounted within the elongated housing, and a deflection system disposed within the elongated housing. The elongated housing has a proximal end, a distal end, and a deflectable segment. The electrode is deployable from a first position within the elongated housing to a second position a predetermined distance beyond the distal end of the elongated housing, and has a flexible portion capable of deflecting with the deflectable segment of the elongated housing. The driver exerts a force sufficient to drive the electrode from the first position to the second position in a single motion. The imaging device has a flexible portion capable of deflecting with the deflectable segment of the elongated housing. The deflection system controllably deflects the deflectable segment of the elongated housing to a desired angle. The deflection system has a proximal end in communication with a steering mechanism.
In one embodiment, the imaging device includes a plurality of illumination optical fibers and a plurality of viewing optical fibers extending from the proximal end to the distal end of the elongated housing. The viewing optical fibers can comprise a fused bundle of viewing optical fibers surrounded by illumination optical fibers, wherein the viewing optical fibers are in communication with a lens disposed at the distal end of the elongated housing. In another embodiment, the electrode is a hollow needle electrode and an insulation sheath surrounds the needle electrode. The needle electrode and the insulation sheath are individually and slidably mounted inside the elongated housing, such that the insulation sheath is capable of covering a proximal portion of the needle electrode which extends beyond the distal end of the elongated housing. In still another embodiment, the driver coupled to the electrode can exert a force within the range of xc2xclb to 1 lb to drive the electrode from the first position to the second position in a single motion.
In another embodiment, the device includes an elongated housing, an electrode mounted within the elongated housing, an imaging device integrally mounted with the elongated housing, a deflection system disposed within the elongated housing, and a foot pedal for deploying the electrode.
In another aspect, the invention features a method for treating tissue. A deflectable interstitial ablation device is inserted into a body lumen which provides access to the tissue to be treated. The deflectable interstitial ablation device includes an elongated housing having a deflectable segment, a deployable electrode mounted within the elongated housing, a driver coupled to the electrode for exerting a force to drive the electrode, an imaging device integrally mounted with the elongated housing, and a deflection system disposed within the elongated housing. The distal end of the elongated housing is positioned near the tissue. The deflectable segment of the elongated housing is deflected toward the tissue, thereby deflecting the electrode and the imaging device toward the tissue along with the deflectable segment. The electrode is deployed to penetrate a wall of the lumen and to position a distal end of the electrode adjacent the tissue. Radio frequency energy is applied to the electrode in an amount and for a duration sufficient to ablate the tissue.
In one embodiment, an insulation sheath is deployed to cover a proximal portion of the deployed electrode to protect the wall of the lumen from directly contacting the needle electrode during the treatment. In another embodiment, a balloon disposed on a body of the elongated housing of the deflectable interstitial ablation device is inflated to secure the position of the elongated housing inside the lumen. In yet another embodiment, a basket disposed on a body of the elongated housing of the deflectable interstitial ablation device is expanded to secure a position. In still another embodiment, the distal end of the elongated housing is connected to an actuator in communication with a foot pedal and the foot pedal is depressed to deploy the electrode.